From 824b307ff7e3e93f2a5d0d864e9161c3db12acfc Mon Sep 17 00:00:00 2001 From: Ariel Ben-Yehuda Date: Tue, 14 Nov 2017 01:24:36 +0200 Subject: [PATCH] avoid the pprust infrastructure in macro expansion This changes macro expansion to format the path of a macro directly instead of usng the pprust infrastructure. The pprust infrastructure tries to perform line-breaking in a slow fashion, which is undesired when formatting the path of a macro. This should to speed up expansion by a fair amount (I saw 20% on a profiler on `rustc_mir`, and 50% of the time marked as "expansion" in the profiler/time-passes is actually spent loading dependencies). --- src/libsyntax/ext/expand.rs | 27 ++++++++++++++++++++++++--- 1 file changed, 24 insertions(+), 3 deletions(-) diff --git a/src/libsyntax/ext/expand.rs b/src/libsyntax/ext/expand.rs index 614c4a10e6d..491dbed01f1 100644 --- a/src/libsyntax/ext/expand.rs +++ b/src/libsyntax/ext/expand.rs @@ -29,6 +29,7 @@ use symbol::Symbol; use symbol::keywords; use syntax_pos::{Span, DUMMY_SP}; +use syntax_pos::hygiene::ExpnFormat; use tokenstream::{TokenStream, TokenTree}; use util::small_vector::SmallVector; use visit::Visitor; @@ -151,6 +152,26 @@ fn expect_from_annotatables>(self, items: I) } } +fn macro_bang_format(path: &ast::Path) -> ExpnFormat { + // We don't want to format a path using pretty-printing, + // `format!("{}", path)`, because that tries to insert + // line-breaks and is slow. + let mut path_str = String::with_capacity(64); + for (i, segment) in path.segments.iter().enumerate() { + if i != 0 { + path_str.push_str("::"); + } + + if segment.identifier.name != keywords::CrateRoot.name() && + segment.identifier.name != keywords::DollarCrate.name() + { + path_str.push_str(&segment.identifier.name.as_str()) + } + } + + MacroBang(Symbol::intern(&path_str)) +} + pub struct Invocation { pub kind: InvocationKind, expansion_kind: ExpansionKind, @@ -517,7 +538,7 @@ fn expand_bang_invoc(&mut self, invoc: Invocation, ext: Rc) -> mark.set_expn_info(ExpnInfo { call_site: span, callee: NameAndSpan { - format: MacroBang(Symbol::intern(&format!("{}", path))), + format: macro_bang_format(path), span: def_site_span, allow_internal_unstable, allow_internal_unsafe, @@ -564,7 +585,7 @@ fn expand_bang_invoc(&mut self, invoc: Invocation, ext: Rc) -> invoc.expansion_data.mark.set_expn_info(ExpnInfo { call_site: span, callee: NameAndSpan { - format: MacroBang(Symbol::intern(&format!("{}", path))), + format: macro_bang_format(path), span: tt_span, allow_internal_unstable, allow_internal_unsafe: false, @@ -600,7 +621,7 @@ fn expand_bang_invoc(&mut self, invoc: Invocation, ext: Rc) -> invoc.expansion_data.mark.set_expn_info(ExpnInfo { call_site: span, callee: NameAndSpan { - format: MacroBang(Symbol::intern(&format!("{}", path))), + format: macro_bang_format(path), // FIXME procedural macros do not have proper span info // yet, when they do, we should use it here. span: None,